Movement responsive light control means



ssa SR BT14591961 v V, l

R. J. RAVAS MOVEMENT RESPONSIVE LIGHT CONTROL MEA-NS Filed April 17,1967 'ausm xR- Aug. 5, 1969 United States Patent O Fice U.S. Cl. 307-1167 Claims ABSTRACT OF THE DISCLOSURE A device for controlling theapplication of power to a load in response to the movement of an objectwithin a prescribed area. The device comprises transmitter means forgenerating and radiating a sound wave having a substantially constantcarrier frequency, means for receiving the sound wave and for producingan output signal in response thereto, a detector circuit connected toproduce an output signal in response to doppler shifts in the frequencyof the received sound wave caused by the object movement, a time delaycircuit connected to produce a switching voltage in response to thedetector circuit output signal, and to remove the switching voltage at apredetermined time after cessation of the movement causing the dopplershifts, and a switching c ircuit connected to apply and remove power tothe load in respective response to the production and removal of theswitching voltage.

Background of the invention The present invention relates generally to acircuit arrangement adapted to control the application of power to aload in response to the detection of movement within the surveillancearea of the arrangement. The invention relates particularly to a soundor sonar light control device adapted to automatically turn on roomlights when one or more persons enter the room, and to automaticallyturn off the lights when the last person leaves the room.

The invention attains two basic objectives, namely, substantialreduction in lighting cost, and the elimination of the need for wallswitches and associated wiring in lighting systems. The invention hasother advantages as will be explained hereinafter. l

Often in factories and oices, lights are continuously left burning sothat if the on time of the lights were reduced only to the 40 hour workweek, the reduction would be to a small percentage of the previous powerconsumption, namely,

40 hours 7 24 hours or 23.8% for a savings of 76.2% in lighting cost.Add to this the savings in lighting costs for areas where lights neednot always be on during the normal working hours, and the possiblesavings realized can go to 90% in lighting cost. The importance of suchan economy is readily seen in regard to large industrial and ofiicebuildings.

With the development and continual expansion of the portable partitionindustry, the elimination of wall switches and wiring would effectfurther considerable savings. Further, such partitions and walls couldbe manufactured, installed and moved without regard for wall wiring andswitch accommodations if automatic light switching devices were employedin say the lighting fixtures.

Brief summary of the invention The present disclosure describes a novel,compact and inexpensive movement sensing device which provides theConsiderable cost saving and other advantages in-light systems explainedabove. The device comprises preferably an 3,459,961 Patented Aug. 5,1969 ultrasonic frequency oscillator energizing av transmitting devicesuch as ceramic transducer, an ultrasonic frequency sensing receiver,which may be another ceramic transducer, miniature (integrated) tunedamplifying circuits, a detector circuit and time delay circuit, and asolid state power switching circuit.

The transmitter radiates a substantially constant frequency ultrasonicsound wave in the room. The ordinary movement of a person or persons inthe room, even though slight, causes a sufficient doppler shift in thefrequency of the sound wave that is detected by the detector circuit.The frequency shift is received and amplified (along with the constantcarrier frequency) by the receiver and amplifiers, respectively, andapplied to the detector which detects the Ifrequency shift by respondingto amplitude variations of the amplified waveform. The envelope waveformis amplified and clipped, producing rectangular pulses which aredirected to the time delay circuit which causes the circuit to produce aswitching voltage capable of gating a switching device'in the powerswitching circuit. This circuit causes energization of the lamp orlighting load. The light or lights are now lit and remain lit as long asthere is motion. When the last person leaves the room, motion ceasestherein so` that the doppler shift frequency no longer exists to bedetected by the detector. The time delay circuit, absent the detectoroutput pulse,

t functions to remove the switching voltage after a time delaypredetermined by the charging time of an integrating capacitor in thecircuit.`This delays the immediate turning off of the lights so that ifthe room is successively frequented the lights will remain on.

By use of integrated circuits and solid state components,

the overall size of the device is such that it can be assembled orinstalled in a light fixture or otherwise packaged to replace the wallswitch thereby updating all existing lighting systems. Installationcosts may be eliminated by adapting the novel device for simple plug-inconnection for standard wall outlets to control a lamp or other loadsconnected thereto.

The drawings The above mentioned and other advantages will become moreapparent with consideration of the following detailed description takenin connection with the accompanying drawing, in which:

FIGURE l is a block diagram of a movement sensing device constructed inaccordance with the principles of the invention; and

FIG. 2 is a diagram of the sensing device of FIG. l in which a portionthereof is shown in schematic circuit detail.

Preferred embodiment Specifically, there is shown in FIG. 1, a blockdiagram representing the stages of the novel movement sensing devicegenerally designated 10. The stages are commonly supplied with directcurrent voltages by a power supply 12 connected across an alternatingcurrent line.

A sound energy producing .oscillator 14 is connected to energize soundtransmitting.or'radiating means 16 with a substantially constantultrasonic carrier frequency. The transmitting means-maybe a ceramictransducer made from such materials-:as barium titanate, lead zirconateor other suitable substances.

The constant carrier frequency is radiated by the transducer 16 asindicated by lines 1S, and the constant carrier reaches a soundresponsive receiving means or microphone 20 as indicated by lines 19.The microphone may be another ceramic transducer identical to thetransmitting transducer 16.

The microphone or receiving transducer 20 is connected to a firstamplifier circuit 22 tuned to the frequency of the constant carriertransmitted by the transducer 16. A second amplifier circuit 24 isconnected to receive the amplified output of the first amplifier, andfurther arnplifies the frequency of the constant carrier.

The second amplifier 24 is provided with an automatic gain controlarrangement for producing a constant level output signal voltage fordetection. This allows the sensing device 10 to be used in substantiallyany size room. The first and second amplifiers are preferably integratedcircuits in miniature package form though the invention is not limitedthereto since other suitable amplifier circuits may be used.

A detector circuit 26 is connected to receive the output of the secondamplifier, and a time delay circuit 28 is, in turn, connected to receivethe output of the detector circuit. The time delay circuit is connectedto produce a switching voltage for energizing a switching circuit 30connected to control the application of AC power to a load 32.

In FIG. 2, the sensing device 10 is shown in further circuit detail.Specifically, the power supply 12 is connected across the AC linethrough a rectifying diode 34 and a voltage dropping resistor 35 on oneside of the line, and a diode 36 forming part of a diode bridge 38 onthe other side. The anode of the diode 36 is connected to a commonconnecting line 39.

A direct current voltage regulator circuit 40 is provided in the powersupply 12 comprising a transistor 41, a transistor base resistor 42, anemitter resistor 43 and a Zener diode 44 connected between the commonline 39 and the base of the transistor.

The detector 26, the delay circuit 28 and a thyristor or SCR firingcircuit 46 are connected to the power supply for B+ voltage through a-resistor 47. A by-pass capacitor 45 is connected between the B+ lineand the comin-ion line 39.

The power supply 12 further comprises an input filter capacitor 48connected across the voltage regulator 40, .a second regulated lowvoltage supply comprising a blocking diode 50, a voltage droppingresistor 51, a filter capacitor 52 and a Zener diode 53. The first andsecond amplifiers 22 and 24 are supplied with the low voltage DC fromthis power supply.

The ultrasonic oscillator 14 is shown comprising a transistor 56, a tankcircuit consisting of a coil 57 and a capacitor 58 connected in thecollector circuit of the transistor, a blocking diode 59 and a grid leaktype of arrangement consisting of a resistor 60 and a capacitor 61 inthe base circuit of the transistor. The oscillator includes a further acoil 62 connecting the base circuit of the transistor to its emitter viathe common connecting line 39, and a resistor 64 connecting B+ supply tothe base circuit of the transistor to facilitate oscillator startup.Other suitable oscillator circuits could be used in place of the onedisclosed. Across the tank circuit is connected the transducer 16.

The detector circuit 26 includes a transistor 70 with its base connectedto the output of the second amplifier and AGC circuit 24 through acoupling capacitor 71 and an RF filter resistor 72. The base and thecollector of the transistor are connected together through a by-passcapacitor 73, the base being further connected to the B+ line by aresistor 74, and the collector connected to B+ through a resistor 75.The emitter of the transistor 70 is connected directly to the commonconnecting line 39 while the collector of the transistor is connected tothe common line through a capacitor 76. Other suitable detector circuitsmay be employed in place of the circuit 26 since the invention is notlimited to the one described.

The time delay circuit 28 includes two cascaded transistors 78 and 79with the base of the transistor 78 connected to the collector (andoutput) of the detector transistor 70 through a blocking diode 80 andresistor 8l. The base of the transistor 78 is connected to its collectorand the collector of the transistor 79 through an integrating capacitor82. B+ voltage is supplied to the collector through a resistor 83 whilethe emitter of the transistor 79 is connected directly to the commonline 39. Other suitable time delay means may be used in place of thecircuit 28.

The switching circuit 30 includes the firing ci-rcuit 46,

a thyristor or cont-rolled rectifying device 85 and the diode bridge 38connected between the gate and the anode terminals of an AC orsymmetrical switching device 86. The input of the firing circuit 46 isconnected to the transistor collectors (and output) of the delay circuit28, and is preferably an integrated circuit in minature package form,for example, the Westinghouse integrated circuit type WC185T describedin Amplifier-SCR Firing Circuit Preliminary Specifications publishedAugust 1966 though the invention is not limited thereto. Other suitablefiring circuits may be employed.

The switching circuit 30 includes further a voltage dropping resistor 88connecting the output of the firing circuit 46 to the gate terminal ofthe controlled -rectifier 85, and a resistor 89 connecting the gateterminal to the common line 39.

The symmetrical switch 86 is connected in series with the lamp load 32across the AC line with diodes 91, 92 and 93 completing the bridgecircuit 38.

In operation, power is applied to the diode 34 in the power supply 12,and to the symmetrical switch 86 by a suitable line switch or othermeans not shown. With no movement in the room under surveillance by thedevice 10, the symmetrical switch is ungated so that the lamp or lightload 32 remains in an off condition. The diode 34 rectifes thealternating current voltage from the line, and the filter capacitorsmooths the resulting DC ripple. The Zener diode 44 and the transistor41 function together to regulate the direct current (B+) voltage withthe voltage at the base of the transistor being fixed by the Zener diodeso that the transistor circuit functions as an emitter follower circuit.Without the transistor 41 working with the Zener diode 44, the regulatorcircuit 40 would be a much less efficient regulating means though otherregulating means may be used in place thereof or in conjunctiontherewith.

The oscillator circuit is energized by the regulated B+ voltage with thecollector of the transistor 56 connected thereto through the tank coil57. Base current therefore -is provided through the resistor 64 and thediode 59. The grid leak type arrangement (comprising resistor 60 andcapacitor 61) in the base circuit provides current fiow through the coil62 which develops a low alternating voltage thereacross for the lowvoltage supply.

The electrical values of the tank resistor 57 and capacitor 58 arechosen to develop a carrier frequency preferably in the ultrasonic rangeso that, when radiated, it will not -be heard by persons in the room orrooms under surveillance. The sound transmitting or radiating transducer16 is directly energized by the electrical energy developed in the tankcircuit, and converts the electrical energy into ultrasonic energy forradiation. The capacitor 45 by-passes any of the carrier frequencyenergy in the B+ line to ground.

The low alternating voltage developed across the coil 62 is rectified bythe diode 50, and filtered and regulated respectively by the capacitor52, resistor 51, and the Zener diode 53. This voltage is supplied to theamplifiers 22 and 24 as shown.

With the ultrasonic carrier radiated in a room, and with no movement inthe room, the carrier is received by the receiving transducer 20 andconverted into elec-I trical energy having the same frequency. Thecarrier frequency is amplified by the two amplifiers 22 and 24, and theamplified carrier is coupled to the detector circuit 26 by the capacitor71. With no modulation on the carrier, the carrier is by-passed aroundthe detector transistor by the capacitor 73, which, in combination withthe resistor 72, forms an RC circuit having'a time con= stant suitablefor such by-pass action.

The capacitor 82 in the delay circuit 28 chargesslowly with a smallamount of B-lcurrent flow therethrough and through the base of thetransistor 78 and 79 to ground. When the capacitor 82 approaches itsmaxi-mum level of charge, the transistor current flows approach zero.

The collector of the transistor 70 is held in saturation unless there issome amplitude variation on the carrier signal coupled to the base ofthe transistor. In that case, collector current pulses are developed anddirected to the delay circuit 28 in a manner presently to be explained.

Thus, with no carrier modulation, the signal to the -base of thetransistor 70 is minimal so that its output signal is minimal which isinsufficient to cause conduction of the diode 80. In a similar manner,no signal is provided to the base of the time delay transistors 78 and79 (except for the small charging current of the capacitor 82) to causeactuation thereof so that the firing circuit 46 is in a quiescent statewith the controlled rectifier 85 and the symmetrical switch 86 remainingungated. The light load 32, receiving no line current through theungated symmetrical switch, is off.

When a person enters the room, or with movement in the room, thefrequency of the sound carrier in the room is modulated by a dopplershift frequency which is received by the receiving transducer 20 andconverted into electrical energy with the carrier. The modulated carrieris amplified by the amplifiers 22 and 24, and applied to the detectorcircuit 26 by the coupling capacitor 71. The

modulating (doppler shift) frequency is detected by the circuit 26 withthe modulation frequency providing a base signal for the transistor 70.The transistor conducts to provide an output voltage capable oftriggering the diode 80 which, in turn, provides a train of voltagepulses across the resistor 81 to the base of the transistors 78 and 79in the delay circuit 28. This causes the transistors to conduct whichprovides a DC output voltage of a level capable of driving the ringcircuit 46. A discharge path is also completed for the capacitor 82 sothat the capacitor rapidly and completely discharges, thereby resettingthe circuit for purposes presently to be explained. The firing circuitproduces a bistable signal which operates to gate the controlledrectifier 85 when the input signal to the firing circuit reaches theprescribed level.

When the controlled rectifier 85 is gated, a DC path is completedthrough the rectifier to the side of the diode 4bridge circuit 38opposite the common line 39. On one half cycle swing of the linevoltage, gate current for the symmetrical switch flows through the diode90, the con-s trolled rectifier 85, the diode 92, and the gate tocathode junction of the symmetrical switch 86. O n the reverse cycle,gate current flows through the direct current supply circuit 12,the'comfmon line 39, the diode 92 and the symmetrical switch as onepath, and through the diode 91, the controlled rectifier 85 and thediode 36 for a second path.

With gate current provided for the symmetrical switch 86 on both halfcyclevswings of the line voltage, the switch conducts for both halfcycles thereby energizing the light load 32. The light will remain on aslong as there is the slightest motion in the room to cause the dopplershift in the frequency of the carrier within the room.

When the last person leaves the room, or when motion otherwise ceases,the carrier frequency will have no doppler shift modulation to bedetected by the detector circuit 26. Consequently, no base signal isprovided to the transistors 78 and 79 in the delay circuit 28 from thedetector circuit. However, the capacitor 82 functioning as anintegrating capacitor now begins to charge with a small B+ current flowtherethrough with the signal to the base of the transistor 78 (from thedetector) being cut off. Thus, the current ow through the charging canpacitor 82 functions to keep the transistors 78 and 79 in an oncondition. B+ current is therefore allowed to ow in the collectorcircuits of the transistors so that an output voltage is maintained witha switching level sufficient to drive the firing circuit 46 in theswitching circuit 30, thereby keeping the light 32 energized with linecurrent fiow through the symmetrical switch 86.

However, as the capacitor 82 approaches its maximum level of charge, thebase current of the transistors 78 and 79 approaches zero so that theoutput voltage required to drive the tiringncircuit 46 is no longeravailable. The firing circuit now ceases to provide the controlledrectifier with a gate signal which, in turn, opens the gate circuit tothe symmetrical switch 86. This opens the load circuit so that thelight-32, in the room, goes out.

Thus the time it takes for the capacitor 82 to charge to near itsmaximum value, is the time it takes for the lights in a room to beturned off after the last motion or movement is detected by the novelsensing device 10. The delay time of the circuit 28 may simply change bychanging the value of the integrating capacitor 82 so that any suitabledelay can be provided for in turning off the room lights after the lastperson leaves.

It should now be apparent from the foregoing description that a new anduseful motion sensing device has been disclosed. The device isparticularly useful yfor detecting the presence of persons within aroom,and for energizing a load, such as room lights, in response thereto.This is accomplished by generating and transmitting a sound energycarrier frequency, and detecting the doppler shift in the carrierfrequency caused by the movements (slight or otherwise) of a person orypersons within the room. A time delay circuit is employed to delay theturning off of the lights after the last movement is detected so thatthe lights in rooms .frequently visited will remain on.

Extreme savings in lighting costs can be effected with the presentinvention as described earlier, as well as providing a compact unitsuitable for mounting as an ordinary wall switch or in a light fixture.The sensing device 10 may be further fconveniently connected in thepower cord of a lamp or other suitable load means.

Though the invention has been describednwith a certain degree ofparticularity, it should be noted that changes may be made thereinwithout departing from the spirit and scope of the invention. Forexample, the device 10 may be employed as a burglar alarm in which casethe light 32 would be an alarm light or other suitable load device.

I claim as my invention:

1. A device for reducing the consumption of power and thus powercostsmby-controlling the application of power to load in response to themovement of an object within a prescribed area, the device comprising:

a transmitter -means for producing a sound wave having a substantiallyconstant frequency,

transducer means for receiving the soundwave and for producing anelectrical output signal in response thereto,

a detector circuit connected to produce an output signal in response toa doppler shift in the frequency of the sound wave received by thetransducer receiving means caused by the object movement,

a time delay circuit connected to produce a switching voltage inresponse to the detector circuit output signal, and to remove theswitching voltage at a predetermined time after the cessation ofmovement causing the doppler shift, and

a switching circuit connected to apply and remove power to the load inrespective response to the production and removal of the switchingvoltage.

2. The device of claim 1 in which the transmitter and receiving meansinclude ceramic transducers.

3. The device of claim 1 in which the switching Circuit includes afiring circuit, a controlled rectier connected to be gated by the firingcircuit, and a solid state symmetrical switch connected to be gated bythe controlled rectifier.

4. The device of claim 1 in which at least one amplifier circuit isconnected to amplify the electrical output signal from the receivingmeans, and

an automatic gain control circuit is connected to provide a signal tothe detector circuit having a constant voltage level characteristic.

5. The device of claim 1 in which the transmitter means includes atransistor feedback oscillator for generating an electrical signal inthe ultrasonic frequency range, and

a transducer means for converting the electrical signal into soundenergy, and for radiating the sound energy at substantially the samefrequence as the: electrical signal.

6. The device of claim 1 in which the time delay circuit is anintegrator circuit employing at least one transistor having its baseconnected to the output of the detector circuit through a blockingdiode.

7. The device of claim 1 in which at least one amplifier circuit isconnected to amplify the electrical output signal of the receivingmeans, and Y a. ring circuit connected to control the gating of acontrolled rectifier in the switching circuit,

the amplifier and firing circuit being integrated circuits in miniaturepackage form.

. References Cited 5 UNITED STATES PATENTS i,

2,788,509 4/ 1957 Bolzmann 315-208 X 2,939,135 5/ 1960 Beckerich et al.,

3,046,519 7/ 1962 Polster.

3,061,758 10/1962 Cobb 315-159 X 10 3,225,265 12/'1965 Krause et al307-157 X 3,242,486 3/1966 Corbel.

3,319,116 5/1967 Schick 315-83 3,331,065 7/ 1967 McDonald 15 ROBERT K.SCHAEFER, Primary Examiner T. B. JOIKE, Assistant Examiner U.S. CI. X.R.20 240-2, 123; 307-140, 157, .252; 328-5; 340-258

